package tools;

/**
 * @Author: sun
 * @Description:int,long,byte[]互转工具类
 * @Data: create in 17:10 2018/12/17
 * @Modfied by:
 */
public class ByteOrderUtils {

    public static byte[] int2byte(int res) {
        byte[] targets = new byte[4];
        // 最低位
        targets[3] = (byte) (res & 0xff);
        // 次低位
        targets[2] = (byte) ((res >> 8) & 0xff);
        // 次高位
        targets[1] = (byte) ((res >> 16) & 0xff);
        // 最高位,无符号右移。
        targets[0] = (byte) (res >>> 24);
        return targets;
    }

    public static int byteArrayToInt(byte[] b) {
        byte[] a = new byte[4];
        int i = a.length - 1, j = b.length - 1;
        //从b的尾部(即int值的低位)开始copy数据
        for (; i >= 0; i--, j--) {
            if (j >= 0) {
                a[i] = b[j];
            } else {
                //如果b.length不足4,则将高位补0
                a[i] = 0;
                }
            }
            //&0xff将byte值无差异转成int,避免Java自动类型提升后,会保留高位的符号位
            int v0 = (a[0] & 0xff) << 24;
            int v1 = (a[1] & 0xff) << 16;
            int v2 = (a[2] & 0xff) << 8;
            int v3 = (a[3] & 0xff);
            return v0 + v1 + v2 + v3;
        }

    public static byte[] long2byte(long res){
            byte[] buffer = new byte[8];
            for (int i = 0; i < 8; i++) {
                int offset = 64 - (i + 1) * 8;
                buffer[i] = (byte) ((res >> offset) & 0xff);
            }
            return buffer;
        }

    public static long byteArrayToLong(byte[] b) {
        long values = 0;
        for (int i = 0; i < 8; i++) {
            values <<= 8;
            values |= (b[i] & 0xff);
        }
        return values;
    }

}
